


Filling in the Hypotenuse

by Caius



Category: Transformers: Beast Wars
Genre: Beast Mode-inspired hardware, Big Rhino cock, Giant rat balls, Jealousy, M/M, Multi, Otherwise pretty standard-issue sticky-style fanon hardware, PWP, Rattrap's version of dirty talk, Slight reluctance/resistance, Sticky Sex, Threesome, Tiny gorilla dick
Language: English
Status: Completed
Published: 2016-02-29
Updated: 2016-02-29
Packaged: 2018-05-23 22:12:47
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,982
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6131752
Author URL: https://archiveofourown.org/users/Caius/pseuds/Caius
Summary: <blockquote class="userstuff">
              <p>Rhinox helps his best friend Rattrap and his simian husband Optimus Primal learn to get along. In bed. Set between <i>Beast Wars, Part 2</i> and <i>The Web</i> but really, it's enough of a PWP that it could be anywhere in Season One.</p>
            </blockquote>





	Filling in the Hypotenuse

**Author's Note:**

  * For [Bunsuu](https://archiveofourown.org/users/Bunsuu/gifts).



"With the boss-ape? Really, Rhino-buddy?" Rattrap crossed his arms, looking at Rhinox with a ruder, more blatant version of Primal's own incredulity. 

"Yes," Rhinox huffed, and picked up the reluctant rodent by the scruff of the neck. Rattrap squeaked in protest; not very seriously, Primal thought. He was starting to learn some of Rattrap's tells, and the way he was wiggling in Rhinox' grip suggested that he was enjoying the display of force. 

Primal could relate. 

Rhinox dropped Rattrap on the berth between Primal's legs, then moved back to take his place behind Primal, warm and solid and protective. Primal nestled himself comfortably into the frame of Rhinox' beast mode's mouth and then leaned his head back, encouraging Rhinox to press a kiss to his lips. 

"Hey, hey, if yer just gonna neck like a coupla birdbots, this rat's headin' out." Rattrap announced. 

Primal shivered as, far from leaving, Rattrap's small body pressed close against his, tiny hands all over his chest, subtle and ticklish and honing in on seams that Rhinox could never exploit. 

"Join us, Rattrap," Primal said, pulling away from Rhinox' lips as he wrapped Rattrap in his arms. 

"Sure, sure--mmph!" Rattrap's next comment was cut off when a familiar large hand pulled his head forward and up, pushing Rattrap's lips against Primal's. 

Up close, Rattrap didn't smell nearly as bad as Primal had expected, the warm fur and ozone comforting, and even when he parted his lips obligingly (encouraged by the soft pressure of Rhinox' teeth on the ruff of fur behind his neck) the taste was...not bad, and the small quick tongue was pleasant. 

Primal moaned softly and pulled Rattrap closer, settling him in between his legs and carefully sliding a hand down his back to rub the prominent ball joints of his aft. 

"Yeah like that..." Rattrap said, grinding a knee against Primal's crotch and raising his opposite leg up to give him better access. "Show me what yer packin'. I can take it..." 

"Ah!" Primal looked back over his shoulder for a moment at Rhinox, a silent _Didn't you tell him?_ interrupted by a kiss and a moan into Rhinox' mouth as Rhinox's large hand reached between them and expertly bared Primal's array to Rattrap's critical gaze. 

Rattrap barked out a surprised laugh and then his small hand replaced Rhinox's. "You didn't tell me it was so _adorable_." Even in Rattrap's hand, Primal's spike was barely enough to hold onto, and Primal's frame heated in embarrassment as Rattrap giggled and pinched and squeezed at it. "Is he a grower, maybe? Is yer banana gonna get any bigger, monkey?"

As embarrassing as it all was, Primal could feel himself getting aroused, his spike swelling to its full three centimeters of length. "That's as big as it gets, Rattrap," he snapped. He reached down between them, pulling Rattrap's hand away from the spike and down where it could be of more use. "Rhinox said _you_ knew how to please a valve." 

Rattrap snickered. "And the big guy told _me_ ya liked a little foreplay. Or a lot." Little fingertips slid around the valve folds, lingering on the places that made Primal shiver involuntarily. 

"Better," Primal said, leaning into Rhinox' warmth and trying to make his annoyance dissolve into the pleasure. When a fingertip breached the entrance, he made his valve ripple around it, pulling it in deeper and smiling just a bit smugly at the gasp and the pop of Rattrap's panel against his thigh. 

"Let's see what _I_ have to work with," Primal said, deep and seductive, half his focus still on coaxing Rattrap's finger deeper into his valve. He reached out for the spike now rubbing slickly against him, wrapping a hand around it -- it was a nice handful, really, nothing like the way Rhinox stretched him, but good enough if Rattrap knew what he was doing. "Adequate," he said, smiling down just to goad him a little, as his hand slid down to the base of the spike and -- oh. Well, this was new. 

"Quite some ball bearings you have." Primal raised an eyebrow, first at Rattrap and then over his shoulder at Rhinox, who, it seamed, hadn't told Primal all of Rhinox' secrets, either. He lifted up the spike to get a better look at them -- two large sacks of pseudoflesh, with a bit of a give to them when he squeezed, wrapped around the ball bearings he had mentioned. Very interesting. 

"The better to -- ahh! Careful, ya ape!" Rattrap squeaked and pulled back, grabbing his own crotch with the hand that had been in Primal's. "Those things are _delicate_!" 

As Primal assessed the situation, torn between alarm and the certainty that Rattrap was exaggerating as usual, Rhinox rumbled gently with laughter behind him. "Up here, Rattrap. Let Primal kiss them better." 

"No teeth!" Rattrap grumbled, and then squealed, "Hey! Warn a rat!" as Rhinox picked him up and flipped him over, presenting his ball bearings to Primal's face. 

Rhinox must have made Rattrap take a bath, was Primal's first thought. Even from this angle, the scent of hot metal and wet fur, pheromones and cybermones, was mouth-watering rather than optic-stinging. He put both hands on Rattrap's aft to stabilize him and pressed his mouth against the balls, kissing and nuzzling gently, exploring the mix of textures and the way Rattrap squirmed and swore down in his lap.

"Ah yeah like that, just a little more..." For a few nano-kliks, Rattrap swung from Primal's hands and mouth, and then he grabbed Primal's own hips firmly and an eager mouth and tongue were wrapped around his tiny spike, sucking furiously. 

Primal nearly bit down on the balls at the sudden suction, but he regained control quickly, gave the ball in gentle kiss in consolation, and, on the thought that turnabout was fair play, licked his way down Rattrap's spike and slid it easily into his mouth.

Rattrap made a garbled sound as Primal swallowed him down easily. Nothing like the satisfying fullness of Rhinox' spike, but it was enjoyable to have some more room to maneuver, to play with his tongue and find Rattrap's weak points. 

Primal spread his legs as he felt Rhinox' arm reach around him. He moaned in satisfaction around Rattrap as Rhinox' broad finger slid into his valve, and then gasped as Rattrap's smaller finger joined it, his lips still wrapped around his spike as he helped Rhinox finger him open. 

Primal's valve clung happily to the fingers, contracting and releasing, showing Rattrap (and Rhinox, who already knew) what he could do for a spike. He moaned happily around the spike, taking it down deep and releasing Rattrap's aft with one hand to massage the balls and consider if maybe he could take one of them in his mouth, too. It still wouldn't be bigger than Rhinox, after all. 

His valve quivered at the thought, pressing up into the fingers as his aft rubbed against Rhinox's crotch. Rhinox' equipment was still covered by his panel, and Primal's aft slid only over smooth metal and soft pseudoskin, the metallic ivory of rhino teeth tingling over his waist as he tried to coax Rhinox out. 

Primal groaned and Rattrap squealed in protest as first Rhinox' fingers were pulled out of Primal's valve, and then strong arms pulled Rattrap out of Primal's mouth and away from his array.

"Hey, hey, I can sit on my own!" Rattrap protested as Rhinox inverted him again and sat him between Primal's legs. "An' anyway from the way the monkey was slurpin' on my banana, he wanted a conversion tank fulla' cream. Din'cha," Rattrap said, poking Primal's belly cheekily. 

"Later," Rhinox said, before Primal could agree with Rattrap. He pulled Primal's legs a little wider open, spreading them out over Rhinox' own, and then, looking over Primal's shoulders, he took hold of Rattrap again, lining him up on his knees and even taking his spike in hand to position it.

"Control freak, not like I don't know how to frag a valve," Rattrap grumbled, but he didn't resist as Rhinox pressed the tip of his spike directly against Primal's entrance and slapped him lightly on the aft. "Ow! Ohhhh!" Rattrap said, both hands grabbing Primal's hips for leverage as the momentum of Rhinox' slap and the strong rings of Primal's valve pulled him inside. 

"Slaaaaag, how're you so tight!" Rattrap said, trying to brace himself against the attempts of Rhinox and Primal himself to set the pace. "With how often ya beg Rhinox to pound ya I figgered I'd have ta fist myself inside yer valve to get any friction but...slag, yeah, like that!" 

"Shut up, Rattrap," Primal told him, but a tight ripple of his valvemesh and a light squeeze to his balls was more effective. 

"Slaaaaaaa!" Rattrap said, his hips pistoning faster, almost pulled back and forth by the way Primal was working his valve. "You ever -- ah!" Rhinox' hand shoved Rattrap's helm into Primal's chest, directly into a sensitive cable to latch onto and suck. 

The tension in Rattrap's body increased, the telltale sign of a bot about to overload who didn't want to, yet. Primal smiled and worked him over harder, anticipating the flood of fluids about to fill him up -- with the balls, he suspected Rattrap could give him even more than Rhinox. 

But before he could force Rattrap over the edge, the bot's clever little hand pressed down between them to rub and squeeze at Primal's little spike, causing him to lose control of the rhythm of his valve working over the spike, pulling it in hard and deep to pleasure himself with it.

Primal held out for a few more thrusts, the dual sensations almost but not quite too much, and then Rhinox shifted him in his arms, the new angle making everything more intense for a moment as Rhinox leaned his head down, past the ruff of fur, to gently and precisely bite at the side of his neck. 

Primal exploded into overload, his valve milking Rattrap hard, pulling out what felt like gallons of conductive fluids that kept the charge going and going. Nodes deep in Primal's valve that Rattrap couldn't reach came online, sending wave upon wave of pleasure through Primal, and just when he thought he was reaching his final peak, he felt Rhinox' spike release against his back and he came again. 

"...Wow," Rattrap said, when the valve finally released him. "Guess that's why they put Optimus in charge." 

Rhinox cuffed Rattrap gently on the side of the head and settled Primal comfortably on the berth, fluid dripping slowly out from between his legs. Rhinox ignored his own arousal for the time being, just holding Primal's hand and letting him recover. 

Rattrap, on the other hand, very definitely noticed. "Ya want me to give ya a hand?" he asked, reaching right over and giving the tip of Rhinox's spike a squeeze. 

Primal made an inadvertent sound of protest. He squeezed Rhinox's hand tighter and pulled his legs apart again. "I want you." 

Rattrap growled low in his throat as Rhinox immediately pulled Rattrap's hand away from his spike and positioned himself between Primal's legs, leaning down to kiss gently at the dripping opening. 

"I see how it is," Rattrap said, growling and turning away. 

But before Rattrap could even get off the berth, Primal took his hand and held him back. "I'd like to suck your spike again -- if you still got the 'cream' to fill up my tanks." 

"Oh slag yeah," Rattrap said, grabbing his own balls lewdly. "Got more'n even you can take right in here." 

"Hurry up and sit on his face then," Rhinox said, looking up from Primal's valve, face streaked with lubricants and transfluid. "It'll be a wild ride." 

Primal shivered and licked his lips, opening his arms and his mouth to help Rattrap up onto him.

**Author's Note:**

> I may continue the porn at a later date, but this seemed like a good stopping point.


End file.
